Certain current gas turbine fuel injection nozzles are utilized in high-hydrogen fuel combustion processes designed to lower NOx emissions. These nozzles incorporate an injection head that contains many small combustion air tubes or passages, trapped between upstream and downstream plates and surrounded by a peripheral wall, forming a hollow body serving as a fuel plenum. The tubes typically include a plurality of very small, low-angle, holes within the walls of the tubes that permit fuel from the hollow body to be injected into the interior of the tubes where the fuel and air are mixed before exiting the tubes and entering the combustion chamber. A fuel injection nozzle of this type is disclosed in commonly-owned U.S. Pat. No. 7,007,478 issued Mar. 7, 2006. Another fuel injection nozzle of this type, formed with a one-piece, monolithic injection head, is disclosed in commonly-owned co-pending application Ser. No. 12/555,129 filed Sep. 8, 2009.
High-hydrogen flame is generally stabilized behind the face of the injection nozzle body and/or dump plane area around the injection nozzle body. The dump area, however, is restricted with the number of injection nozzle heads in a full can combustor to overcome the large pressure drop through the tube bundles. As a result, only the injection nozzle head face area can be used for high-hydrogen flame stabilization. Current injection nozzle heads likewise have only limited areas for stabilizing the flame. It would therefore be desirable to develop ways to improve injection nozzle head design to further optimize high-hydrogen combustion flame stabilization, improve flashback margin and further reduce NOx emissions.